I've not had this problem, although I know use all share and stream via my media steamer

 

This is a known problem that the charge trickles down despite the charging input.

I use my Mugen Extended Battery for longer MHL sessions, there are a number of extended battery options out there that might be worth exploring.

 

I had this issue while playing a game before i upgraded 2.3.4 now it is resolved

 

What is the power rating of the charger? Some acre only 500mA or 750mA. If you have a higher rated one r them it should fix the problem? Maybe 1000 or even 1500mA. Sanger voltage of course

 

A higher input charger perhaps could solve this, although I'd be worried about the safety of doing that.

 

I assume the brightness is adjusted to its lowest level?

 

Maybe put the phone in aeroplane mode to kill the 3g and data connections, and make sure wifi and all of the gps settings are off?

 

There's no point. The SGS2 caps the current it will draw to 600mA on USB cable or 750mA on a mains charger. Plugging it into a higher powered charger won't make any difference unfortunately.

 

Wow, I finally found some info on this. Thought it was just me.

There are supposed to be some rooted kernels that can increase current draw but I don't know how to change the current draw on these kernels in a safe manner.

Pretty crazy that samsung has this problem stock, especially when they are releasing TV's that are supposed to charge the phone though an hdmi/mhl cable.

I notice too that the cpu seems to max out during video playback so it's not just the screen being on.

This doesn't seem to be much of a priority on xda yet since so few havethe cables but now that you can get them for $15 off ebay and netflix released there app for all 2.3+ phones.. it soon will be.

 

I have used the phone to watch movies (2.5 hrs long) via MHL cable while on stock ROM and now cognition 1.5.1. I always see an increase in the charge percentage after the movie has completed playing. So there may be a problem with your settings.. I use juice defender which shuts down data/wifi if not used and so on...